- Hydroxypropyl beta cyclodextrin (HPBCD) is being tested for a disease called Niemann-Pick disease type C1 (NPC1). NPC1 is a genetic disorder that results in gradual loss of nervous system function. Cholesterol and other fats have trouble moving out of the brain cells, which makes the cells work poorly and leads to symptoms. There is no treatment currently approved in the US for NPC1. Researchers want to test if it is safe to use HPBCD for NPC1. They want to see if it can help brain cells process cholesterol better.